Crowds are gathering at a Vancouver conservatory to witness the rare blooming of an exotic plant known for its size and stench.

A news release from the Vancouver Park Board says the titan arum, the largest flower on earth, began to bloom Sunday evening — and began to smell.

“When it opened last night at around six, or when it started to, you could smell what I say smells like a dead rat to me,” said Bruce McDonald, superintendent at Bloedel Conservatory and Sunset Nursery.

“By about 11 o’clock, you could get close to the back of it and smell it.”

Over 24 to 28 hours the plant, better known as the corpse flower because of its powerful stench, releases an aroma that has been described as similar to rotting flesh, discarded diapers or hot garbage.

“It’s this beautiful thing that couldn’t smell any worse,” said McDonald.

When McDonald came into the conservatory early Monday morning, the stench was “full on” from the back of the building.

Bruce McDonald, superintendent at Bloedel Conservatory, says the blooming flower caught them all off guard.(Margaret Gallagher/CBC)

‘Rotting piece of meat’

The smell is part of the plant’s pollinating mechanism.

The park board says the nearly two-metre tall flower produces the smell and a deep-red flesh colour inside the open petal in order to attract pollinator insects like carrion beetles and flesh flies that feed on dead animals.

“What they want to do is find that rotting piece of meat and come lay their eggs on it,” McDonald said.

The spike of the rare flower even self-heats to approximately human body temperature while the petal unfurls, to better spread the putrid scent.

It takes titan arumas long as 10 years to produce its single spike-like bloom, which is wrapped by a funnel-like petal.

The lineup to see (and smell) the flower, which is expected to emit its stench for up to 48 hours, stretched out front of the Bloedel Conservatory on Monday morning. (Margaret Gallagher/CBC)

It’s the first time the plant, native to Sumatra, has bloomed in B.C.

“They are really unpredictable, you just never know what’s going to happen with them,” said McDonald. “It caught all of us off guard.”

The Vancouver Park Board said horticulturalists noticed that a 28-centimetre flower bud had formed on June 21. Now it measures almost two metres.

“Uncle Fester,” as the plant has been dubbed, is on display at the Bloedel Conservatory in Queen Elizabeth Park, with extended viewing hours beginning at 7 a.m. Monday, so the curious and the brave can get a whiff.

The smell is expected to be most intense on Monday but will linger for 48 hours.